Protecting the skin from damage due to ultraviolet rays is an important problem in skin care and body care, and various UV-care cosmetics for minimizing the harmful effects of ultraviolet rays on the skin have been developed. Sunscreen cosmetics, which are a type of UV-care cosmetic, are cosmetics that protect the skin from damage due to ultraviolet rays by containing an ultraviolet ray absorbing agent or an ultraviolet ray scattering agent, thereby blocking UVA and UVB rays from reaching the skin (Non-Patent Document 1).
As types of sunscreen cosmetics, formats in which a lotion stored in a container is taken in the hand and applied to the skin and formats in which the cosmetic is sprayed directly onto the skin are known, and various properties are required depending on the format. For example, for sprayable sunscreen cosmetics, it is necessary to prevent blockage of the nozzle due to aggregation of powder ingredients such as ultraviolet ray scattering agents.
Patent Document 1 describes an aerosol-type sunscreen cosmetic wherein the powder dispersibility is improved by dispersing an inorganic oxide powder such as an ultraviolet ray scattering agent in an oil-based liquid containing a specific lipophilic solvent (ester oil), alcohol and an ultraviolet ray absorbing agent. However, while lotion-type sunscreen cosmetics are spread by the hand, thus mitigating their whiteness, sprayable sunscreen cosmetics such as aerosols are often not spread after being sprayed on the skin, and are required to be transparent immediately after being sprayed. For this reason, they preferably do not contain ultraviolet ray scattering agents that cause whiteness.
However, in order to obtain excellent ultraviolet ray protection effects (high SPF (Sun Protection Factor) and high PA (Protection Grade of UVA)) in a sunscreen cosmetic that does not contain an ultraviolet ray scattering agent, it is necessary to add large quantities of ultraviolet ray absorbing agents for the UVA and UVB ranges, and the amounts of oil-based solvents (polar oils or the like) that are blended must also be increased in order to dissolve these ultraviolet ray absorbing agents, resulting in problems such as sensations of oiliness or stickiness when used.
Patent Document 2 discloses a spray-type sunscreen cosmetic that contains substantially no powder ingredients such as ultraviolet ray scattering agents, and that protects against ultraviolet rays in the UVA to UVB ranges by means of an ultraviolet ray absorbing agent. The document describes that a cosmetic providing a long-lasting sensation of freshness without causing coarseness is obtained by setting the blended amount of lower alcohols to 80 to 85 mass % and setting the blended amounts of silicone and water to about 5 mass % or less. However, it is difficult to dissolve all of the ultraviolet ray absorbing agents by blending in large quantities of alcohol, and there are concerns about problems such as the precipitation of the ultraviolet ray absorbing agent over time.
On the other hand, when sunscreen cosmetics that have been applied to skin come into contact with water or perspiration, the ultraviolet ray absorbing agents and ultraviolet ray scattering agents can flow out from the applied cosmetic, and decreases in ultraviolet ray protection effects are unavoidable. For example, even if a cosmetic contains large quantities of resins or film-forming agents in order to provide water resistance, it is still difficult to completely prevent the outflow of ultraviolet absorbing agents, ultraviolet scattering agents or the like. Additionally, it was thought that, even if the outflow of ultraviolet ray absorbing agents or the like could be entirely prevented, the resulting ultraviolet ray protection effects would never be superior to the effects immediately after application.